Energy healing therapies such as Reiki are becoming popular. Reiki is a spiritual practice that involves physical touch and social contact with an empathetic person; unlike many relaxation therapies, Reiki requires no participation by the patient. These features make Reiki particularly attractive in the hospital setting, where patients are often extremely anxious, depressed, in pain, or sedated. In this setting, stress can be associated with increased pain, cardiovascular reactivity, decreased wound healing, increased susceptibility to infectious disease, increased post-surgical complications, and increased length-of-stay. Although Reiki is commonly used in the hospital setting to reduce pain or pre-surgical anxiety, there are few studies demonstrating benefits. Remarkably, no information is available on physiological changes induced during a Reiki session. In the absence of such information, it is difficult to make rational predictions concerning situations in which it may be beneficial. Moreover, given the deep state of relaxation often reported by clients, we cannot exclude the possibility that it may have a potential for harm in certain medical situations. Our primary research questions are to determine whether physiological changes are induced during a Reiki session and whether a Reiki session affects responses to a subsequent acute stressor. Secondary research questions include assessing which benefits result from placebo, empathetic intentions, or unique abilities of "attuned" Reiki practitioners and assessing background characteristics associated with acceptance and responsiveness. Based on its use to reduce pain and anxiety, a potential mechanism by which Reiki might exert effects is at the level of affecting emotional centers of the brain with resulting decreases in activity of the SNS and other stress pathways. To assess these possibilities, we will perform a randomized, controlled, blinded study with four groups of 80 healthy volunteers. In Specific Aim 1, we will assess changes in physiological markers of sympathetic, parasympathetic, and HPA activation, brain activity, and psychological well-being before and after a 30-min session of Reiki, as compared to control groups. In Specific Aim 2, we will assess the ability of Reiki to affect psychological, sympathetic, parasympathetic, HPA, immune function, and platelet activation responses to an ensuing 5-min acute laboratory stressor. The use of supine-control, neutral sham, and empathetic sham groups will allow us to gain insights into mechanisms by which Reiki effects are mediated. Interactions between baseline characteristics and treatment effects will be assessed. Information obtained from the proposed studies will provide detailed information on physiological pathways affected by Reiki. This information is critical if we are to make rational decisions on potential situations in which Reiki sessions may provide benefits and those in which there may be the potential for harm. Should Reiki decrease stress pathways or reduce physiological responses to stressful situations, it could be a powerful adjunct to traditional medicine and have enormous health and economic impact.